SURFACES AND INTERFACES: NANOFABRICATION, IMAGING, AND SPECTROSCOPY

The Institute activities concerning surfaces and interfaces: nanofabrication, imaging, and spectroscopy point at optimizing important functionalities in materials through an atomic scale understanding of the modifications introduced by confinement. The materials are produced in the Institute laboratories and controlled through the combination of high resolution spectroscopies, microscopies and theoretical simulations. The activities are performed also at shared facilities, like synchrotron radiation sources and transmission electron microscopes. An important piece of activity concerns in particular the development of analysis techniques based on electron vortex beams.

Graphene-based materials with tunable electronic, optical, structural, and mechanical properties are developed and manipulated in view of the application in different fields. An interesting possibility is given by the use of graphene for hydrogen storage. In this context the Institute activities have shown that the hydrogen storage capacity of the material can be enhanced by the rippling induced by the interaction with specific substrates and by the presence of metal clusters. Light-weight metal intercalation is also favored by the corrugation. In graphene nanoribbons, extraordinarily versatile semiconducting materials, the optical and electronic behavior of each atomic species has been identified, opening the way to promising applications in nanoelectronics and optoelectronics. Moreover, the unique mechanical properties of graphene have been exploited in view of the development of efficient ultrathin lubricant and antiwear coatings. In this context the mechanisms which induce a lower friction on realistic and extended graphene coatings have been investigated.

Researches concerning the development of defect-free nanowire semiconductor heterostructures focused on the understanding of nanoparticle-nanowire interactions during the metal-assisted growth. The activities, involving high-resolution imaging and modelling, lead to important results towards the achievement of a full control over the morphology and the properties of the systems.

The activities concerning oxide-based systems focused on transparent conducting and reducible oxides, of interest for energy and environmental applications. In transparent conducting oxides the optical and electronic modifications induced by highly diluted elements and by the additional defect species have been identified. In reducible oxides the proximity of metal species, reduced dimensionality and defect distribution have been shown to largely influence the reducibility, a property on which the diverse applications of the material are based.

Flexible piezoelectric materials enable ultra-high pressure sensitivity and integration in accelerometers and nano-generators. The Institute activities focused on the understanding of the nanoscale interactions responsible for the piezoelectric mechanisms in individual polymeric nanowires and on the realization of more complex light-emitting systems.

Recent important results on the application of large orbital moment electron vortex beams concern the development of innovative methods for the measurement of magnetic fields. The Institute researchers exploited their first observation of the vertical Aharonov-Bohm effect as a new approach to quantify the longitudinal component of magnetic fields. To determine the transverse component, they developed a method which converts the magnetic phase into an amplitude by a unitary transformation of the wave function, achieved through new holographic elements.